The effects of the presence of a uniform magnetic field on the growth rate and the threshold intensity of the two-plasmon decay in a homogeneous plasma have been investigated. Analytical expressions for the growth rate and threshold intensity have been obtained. It has been shown that the presence of a magnetic field affects significantly the growth rate and the threshold intensity for the two-plasmon decay.

The effects of an axial magnetic field on the convective amplification and the threshold intensity of Raman backscattering instability in an underdense, inhomogeneous plasma is investigated. Two cases of incident pump wave were considered. For the R-circularly polarization case it is shown that the amplification factor increases with the magnetic field, it also increases with the plasma density while the threshold intensity decreases. For the L-circularly polarization case, it is shown that the amplification factor decreases as the magnetic field and the plasma density increase, while the threshold intensity increases as the magnetic field increases but it decreases as the plasma density increases.